Compositions containing metal dialkyl dithiophosphates are inhibited against haze and precipitates by amine salts of mixed acid phosphates

ABSTRACT

AMINE SALTS OF MIXED ACID PHOSPHATES ARE COMBINED WITH METAL DIALKYL DITHIOPHOSPHATES TO PREVENT AND CONTROL HAZE AND PRECIPITATION IN COMPOSITIONS CONTAINING THESE DITHIOPHOSPHATE SALTS.

United States Patent COMPOSITIONS CONTAINING METAL DIALKYL DITHIOPHOSPHATES ARE INHIBITED AGAINST HAZE AND PRECIPITATES BY AMINE SALTS OF MIXED ACID PHOSPHATES Jack Ryer, East Brunswick, and Remi H. Renard, North Brunswick, N.J., assignors to Esso Research and Englueering Company No Drawing. Filed June 30, 1972, Ser. No. 268,146

Int. Cl. Cm 1/48 US. Cl. 25232.7 E 4 Claims ABSTRACT OF THE DISCLOSURE Amine salts of mixed acid phosphates are combined with metal dialkyl dithiophosphates to prevent and control haze and precipitation in compositions containing these dithiophosphate salts.

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to new chemical compositions and to lubricating oils containing these compositions. More particularly, this invention relates to a novel class of chemical compositions containing dialkyl dithiophosphates which do not exhibit undesirable precipitation and haze formation.

Description of the Prior Art Metal dialkyl dithiophosphates are metal salts of dialkyl dithiophosphoric acids and are well known additives for lubricating oil compositions. This class of metal salts is particularly useful as antiwear, corrosion inhibitor, and anti-oxidant additives for lubricating oils used in internal combustion engines.

Compositions containing metal dialkyl dithiophosphates (DDP) frequently suffer from the development of haze or precipitates when small amounts of water, such as 50- 500 ppm, are present in these compositions. Such small amounts of water typically enter lubricating oil compositions by condensation of atmospheric moisture, see page, etc., and it is difficult to keep these compositions waterfree.

The development of haze may be due to the water itself or to a product formed by a reaction of water with DDP. Heat favors the reaction of water with DDP, and the problem of haze formation caused by this reaction is particularly pressing because compositions containing DDP are often kept hot for prolonged periods, for example, during tank car transport. Precipitation can result from interaction of the water with the DDP salt.

Haze and precipitation free lubricating oil compositions are obviously more marketable than hazy compositions.

In the past, barium sulfonate has been used for water dispersion in DDP-containing compositions in an attempt to prevent haze formation. This technique only works, however, if the composition is not heated for prolonged periods. Accordingly, the use of barium sulfonate does not provide an entirely satisfactory solution, and continuing search goes on for an additive composition containing DDP which avoids haze formation and precipitation problems.

3,825,745 Patented July 30, 1974 "ice SUMMARY OF THE INVENTION It has now been discovered that certain amine salts of acid phosphates can be added to compositions containing metal dithiophosphates to prevent precipitation and haze formation in these compositions. Such amine salts are effective in preventing haze formation even through the composition is heated to temperatures which normally promote the formation of haze and precipitates. The compositions of the present invention, therefore, can be pumped at elevated temperatures without haze formation.

The amine salts of the present invention are also effective in correcting and clearing compositions in which haze has already developed. The haze free compositions are prepared by forming a mixture of the amine salts and DDP, and heating the mixture for about at least 6 hours or more at a temperature of about at least F.

DETAILED DESCRIPTION In accordance with the invention, the metal dialkyl dithiophosphates used in the present invention have the general formula:

s Rats]...

wherein R and R are the same or different hydrocarbyl groups having from 3 to 12 carbon atoms and M is zinc, cadmium, barium, nickel or magnesium. Preferably, R and R are identical groups having from 3-8 carbon atoms and M is zinc. It is understood that DDP salts may also contain minor amounts of monohydroxide salts of the general formula:

where R, R and M are as just defined.

The metal dialkyl dithiophosphates can be obtained commercially or can be prepared by conventional methods well known in the art. For example, metal dialkyl dithiophosphate can be prepared by reacting phosphorus pentasulfide with an aliphatic alcohol, a mixture of aliphatic alcohols, or phenols containing the desired range of hydrocarbyl groups in a molar ratio of approximately 4 moles of alcohol for each mole of phosphorus pentasulfide. This forms the corresponding dialkyl dithiophosphoric acids, and these acids are neutralized with an oxide, hydroxide or carbonate of a polyvalent metal, or alternatively with a reactive polyvalent metal salt to form the metal dialkyl dithiophosphate.

The present invention employs polyvalent metal salts of dialkyl dithiophosphoric acids prepared from alcohols having from about 3 to about 12 carbon atoms. The dialkyl dithiophosphoric acids whose salts are used in this invention include those made from a simple aliphatic alcohol such as isopropyl, normal butyl, normal decyl, etc. They also include those made from mixed aliphatic alcohols including the C or C alcohols obtained by reaction of olefins with carbon monoxide and hydrogen, and subsequent hydrogenation of the resultant aldehydes. These alcohols are known as 0x0 alcohols. Dithiophosphoric acids obtained from mixtures of isopropyl a s9holami meth isobutyl hol and isobutanol, mixed anyl alcohols and technical lauryl alcohol, mixtures of isopropyl alcohol and C Oxo alcohol, and the like can also be used. Mixed acids obtained by individual reaction of selected alcohols with P 8 can also be employed in the preparation of the metal salts.

The metals employed in making the salts are those of Group II of the Periodic Table including zinc, cadmium, barium and'inagnesium. Nickel can also be used. Zinc salts arev particularly preferred.

In accordance with the present invention the metal DDP salt is mixed with an amine salt of a dihydrocarbyl acid phosphate having the general formula:

wherein x is 1 or 2, R is a C to C 5 hydrocarbyl group, R and 'R each are a hydrogen atom or C to C hydrocarbyl group, and R is selected from the group consisting of (a) C to C hydrocarbyl groups or mixtures thereof,

(b) amino hydrocarbyl groups of the formula where x is l or *(-CH -),,N+H R when x is 2, wherein n is 2 or 3 and R is (a) above; and (c) alkylene polyamino groups of the formula tCl-l CH NHi H wherein m is an integer between 2 and 4.

Preferably, R and R are each hydrogen atoms or C to C alkyl groups, and R is (b) wherein R is a substantially linearC to C aliphatic group. Examples of said amine phosphates include a commercial amine phosphate consisting of an 80% solution of amine salt of mixed alkyl acid phosphates in kerosine. In this preferred amine, R is the hydrocarbyl portion of a C x0 alcohol, R and R are H, and R is Other amine phosphate salts generally suitable for use in the present invention include compounds of the structures:

(C13H27O)1P O2NHa( 1)aCH3,

CHzCHa (CgHnO) 2P OzNHzCHzCH (CH2) aCHa and The additives of the present invention are prepared by forming a mixture of the metal dialkyl dithiophosphate and the amine salt of the dihydrocarbyl acid phosphate and heating the mixture for about at least 6 hours at a temperature of about at least 140 F. Preferably, the mix- "ture is heated at temperatures from about 140 F. to about 180 F. for about 6 to about 24 hours.

" The 'additives'of the present invention contain about 0'.'005"to 0.5 parts by weight of the amine salt per part of dithiophosphate salt. When used as additives, the composition is incorporated in lubricating oils in concentrations from about 0.5 to 50 Weight percent active ingredient', preferably 1 to about weight percent. The final oil compositions formed 'to include the additives of this invention have a dithiophosphate content of about 0.1 to 1.0% byweight, preferably about .2 to 6% by Weight, and an amine salt content of 0.0005 to 0.5% by weight, preferably about .001 to 0.3% by weight. The concentration will vary with the particular metal dialkyl dithiophosphate salt used, the particular base stock employed,

carbinol, primaryamyl alcoand the function of the additive; i.e. Whether it is. to .be simply an anti-oxidant or whether it is also to serve as a corrosion inhibitor, wear reducing or extreme pressure agent.

The additives of this invention can be added to any conventional type lubricating oil including animal and vegetable oils as well as mineral lubricating oils and synthetic oils. The mineral lubricating oils can be of any preferred type, including those derived from the ordinary paraffinic, naphthenic, asphaltic, or mixed base mineral crude oils by suitable refining methods. Suitable synthetic oils include synthetic hydrocarbon lubricating oils, as well as dibasic acid esters such as di-2-ethyl hexyl siebacate, carbonate esters, phosphate esters, halogenated hydrocarbons, polysilicones, polyglycols, glycol esters such as C oxo acid diesters of tetraethylene glycol, and complex esters, as for example, the complex ester formed by the reaction of 1 mole of sebacic acid with 2 moles of tetraethylene glycol and 2 moles of 2-ethyl hexanoic acid.

While the lubricant compositions herein described are primarily used as internal combustion engine crankcase lubricants, they may also be employed in'other oil compositions, including turbine oils, various industrial oils, gear oils, hydraulic fluids, transmission fluids and the like.

It is within the contemplation of this invention to prepare easily handled liquid additive concentrates in which the concentration of additive is greater than would normally be employed in a finished lubricant. These concentrates may contain in the range of from 10 to 75% of additive (metal DDP plus amine phosphate salt) on an active ingredient basis, the balance being a petroleum fraction such as mineral oil, kerosene, etc. Such concentrates are convenient for handling the additive in the ultimate blending operation into a finished lubricating oil'composition. The additive concentrates can be made up simply by combining the metal DDP and amine phosphate salt of the present invention in a suitable mineral oil medium.

The additive package can also include effective amounts of other additives that are intended forum in a finished lubricant. These additional additives can each be present in amounts up to about 20% by weight of the finished lubricating oil composition. Such additives include, for example, detergents and dispersants of the ash-containing or ashless type, oxidation inhibiting agents, viscosity index improving agents, pour point depressants, extreme pressure agents, color stabilizers and anti-foam agents.

Suitable additives of these types are known in the art. For example, crankcase lubricating oils can contain polymers such as polyisobutylene, polymethacrylates, copolymers of alkyl fumarateswith vinyl acetate and various other long chain polymers usually having molecular weight of about 5,000 to 100,000 as viscosity index improvers and pour point depressants. Oxidation inhibitors frequently used in such compositions include, for example, phenyl a-naphthylamine, and detergent additives include metal salts of alkyl phenol sulfides and complexes of various P 8 treated hydrocarbons neutralized with metal bases or metal salts of other materials such as phenols, sulfonates, carbonates and the like.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following examples will serve to illustrate methods of preparing the compositions of this invention and include preferred embodiments of said invention.

EXAMPLE 1 from a mixture of acids derived from isobutyl alcohol and 35% primary amyl alcohol; (3) 3.00 volume percent of Solvent 150 Neutral (S150-N); and (4) 0.25 volume percent of an Weight percent solution of an amine salt of mixed alkyl acid phosphates in kerosine. This amine salt was one wherein the alkyl phosphate cooled to room temperature. The mixture retains its clear yellow color and no haze formation is observed.

EXAMPLE 2 The procedure of Example 1 is repeated except-that 5 different amounts of the ingredients are mixed together as set forth in Table 2 below:

TABLE 2 Vol. Specific Wt. in Wt. Ingredients percent gravity gms. percent Polyisebutylene in S-150N 05. 75 8892 284. 19 94. 73 Zn dlalkyl dithiophosphate in 1.00 1. 1265 i 3. 72 1. 26 S-160-N 3.00 8681 11. 28 3. 76 Amine phosphate salt in 0. 25 9128 75 25 kerosine.

Total 100. 00 300. 00 100. 00

group (R were derived from a C Oxo alcohol, R and R are hydrogen atoms and R is This particular solution of amine salt was used in all the following examples.

The Solvent 150 Neutral is a diluent oil sold by Humble Oil .Refining Co., Inc. and has an aniline pt. of 64 F., a minimum flash point of 151 F., and a specific gravity The oil blend is heated at 140 F. for 6 hours, and the resulting composition is a clear amber liquid.

Water at a level of 500 p.p.m. is added as in Example 1. The mixture is stored for 3 days at 180 F. and then cooled at room temperature. The mixture retains its amber color and no haze formation is observed.

EXAMPLE 3 The procedure of Example 1 is repeated except that TABLE 1 Vol. Specific Wt. in Wt. Ingredients percent gravity gms. percent 1 Polyisobutylene in S150N 93. 75 8892 279. 21 93.07 2 znirllialkyl dithiophosphate in 3.00 1.1265 11.31 3. 77

o N 3.00 .8681 8. 70 2. 4 Amine phosphate salt in 0. 25 9128 78 26 kerosine. Total -2 100. 00 300. 00 100. 00

at 60 F. of 0.891. The weight percent of each ingredient in the oil blend is shown in Table 1.

different amounts of the ingredients are mixed together as set forth in Table 3 below.

The oil blend is heated at F. for 6 hours. The resulting composition is a clear, yellow liquid and has the following properties:

The oil blend is heated at 140 F. for 6 hours, and the resulting composition is a clear amber liquid.

Water at a level of 500 p.p.m. is added as in Example e ifi ravit .8877 25 7.392 1. The mixture is stored for 3 days at 180 F. and then Gravity API 27 9 coo ed at room temperature. The mixture retains its amber Viscosity at 210 F., c./s. 523 Color and no haze formation is observed. Flash Point F. (Cleveland Open Cup) 390 5 Color ASTM 2.0 EXAMPLE 4 in ontent t. ercent 0.35 a i f fi wt percent 033 The proced re of Example 1 is repeated except that (joefii i nt f Thenflal Expansion 00 different amounts of the ingredients are mixed together Barium Content, wt. percent .04 as set forth in Table 4 below.

TABLE 4 Vol. Specific Wt. in Wt. Ingredients percent gravity grns. percent 1 Polyisobutylenein SN 93.75 .8892 279.15 93.05 2 Zn dialkyl dithiophosphate in 3. 00 1.1265 11.31 3. 77 a siip-N 2. 75 .8681 8.01 2.67 4 Amine phosphate salt in 0.50 .9128 1.53 .51

kerosine.

Total 100.00 300. 00 100.00

This oil blend is tested for haze formation by adding 500 p.p.m. of water to it. The Water and oil blend are mixed in a General Electric Mixer Model 5BA60V222 that is operated at maximum r.p.m. for two minutes at room temperature.

The oil blend is heated at 140 F. for 6 hours, and the resulting composition is a clear amber liquid.

Water at a level of 500 p.p.m. is added'as in Example 1. The mixture is stored for 3 days at 180 F. and then cooled at room temperature. The mixture retains its amber The mixture is stored for 3 days at 180 F., and then 75 color and no haze formation is observed.

7 8 EXAMPLE A second set of aliquots is stored 'for 3 days at l80"*F. and

then cooled for observation. The results are' set fdr'th Two oil blends are prepared by following the procebelow dure of Example 1 except that different amounts of the i p 7 ingredients are mixed together as set forth in Table 5 After3days f storage at 180 below. J After 24 hours F. and cooling at room for observa-' P.p.1n. H20 temperature tion TABLE 5 Volume percent Ingredients Comp.A Comp. B

1 2 5 11 130 as 2 't' t oi 3 s 150 N .232K 12: 3.15 3. 00 The hazy ahquots contammg 100 and 200 p.p.m. that 4 Amme Phosphate salt kemsme have been stored for 3 days at 180 F. and then cooled 15 are cleared up by adding 0.25 volume percent of amine phosphate and heating at 180 F. for 12 hours.

The oil blends are heated at 140 F. for 6 hours, and MP E 7 I 7 i116 resultlllg COIIIPOSIUOHS are Clear q A number of other control blends are prepared using Varying amounts of water from 100 to 500 p.p.m. are added to aliquots of each oil blend. A first set of aliquots for each blend is stored for 3 days at 180 F. and then cooled for observation. A second set of aliquots for each various combinations of barium sulfonate and a C Oxo alcohol in an attempt to produce haze freecornpositionsl The C Oxo alcohol used is a primary alcoholfmade by treating l-dodecene with carbon monoxide in the presence of an Oxo catalyst, see Applied Organic Chemistry,

by Kilner and Samuel, Interscience Publishing, Inc., New

TABLE 7 Comp. 0 Comp. D Comp. E I Comp. F Comp. G

V01. Wt. Vol. Wt. V01. Wt. Vol. Wt." Vol. Wt. percent percent percent percent percent percent percent percent percent percent 1 Polyisobutylene in S150N 04.00 03.41 03.75 03.10 93. 75 93.06 94. 00 03. 04.00 03.00 2 n dialkyl dithiophosphate in 011.. 3. 00 3.77 3. 00 3. 77 3.00 3. 77 3.00 3.78 1 1.0 1.27 3 S150-N 1.50 1.45 1. 50 1. 3.5 3. 42 4 C oxo 3.00 2. s2 3. 00 2. 82 1.50 1.41 1.50 1.41 1.5 i 1.41 5 Barium sulfonate in oil 0.25 .31 0- 25 31 blend is stored at room temperature for 24 hours and ob- York, 1960, p. 43. The C Oxo alcohol used has a specific served. The results are set forth below. gravity of 0.8400.

The above table lists the compositions tested. A 3 d t t All of the above blends are tested for haze formation by S S cm 0 3' After 24 hm 1.00m 3 addmg 500 p.p.m. of water, storing them at 180 F. for temperature observation 3 days, and then cooling to room temperature. All of the Rpm H2O Comm A Comp B com A Comm B blends exhibit significant haze formation showing by com- 100 ht h 1th 01 01m 4? parison the improved results achieved by the composition nheufiiiii 112%..35211125221111 b 150. 0 of the present invention in the preceding examples.

Slighthaw- The invention in its broader aspects is not limited to d Hazy. Y 1 00 do do do Do. the speclfic eta ls Shown and descrlbed and departures may be made from such details without departing'from EXAMPLE 6 the prlnclples of the invention and Without sacrificing its chief advantages. 7 ThlS example demonstrates the advantages of the pres- What is claimed m inventipn as compared with the priorart method of 1, An additive composition of improved resistance to adding banum Sulfonate to mefal dlalkyl dlthlophosphatshaze and precipitate formation which comprises a-metal The Procfidufe of Example 1 fepgated P- that dialkyl dithiophosphate wherein the metal is zinc, barium, Volume Percent of P contammg 45 to 48 cadmium, magnesium or nickel and said alkyl groups conweight percent of ba um Sulfonate sold under h name tain 3 to 12 carbon atoms; heated to at least about 140 F. Bryton Hibas B iu Sulfonate y Y P Chemlcal Cow for at least about 6 hours with about 0.005 to 0.5 parts Saddle Br k, and 55 to 52 Welght Feniant of a by weight, per part of said dithiophosphate, of an amine petroleum diluent oil is added instead of 3.00 volume per- Salt of dih drocarb 1 acid hos hat of th t cent of the composition containing the amine salt of mixed y y p p e e s ructure alkyl acid phosphates. 0

' 1 2 8 The 011 blend has the followmg compos1t1on: (Rfio) i o R R Vol. Specific Wt. in Wt. Ingredient percent gravity grns. percent 1 Polylsobutylene in S150-N. 93. 8802 465. 10 93.02 Zn alkyl dithiophosphate in oiL- 3.00 1.2165 18. 3.77 S150N 3.00 .8681 14. 50 2. ,4 Barium sulionate in oil 25 1. 1172 1. 55 31 Total 100. 00 500. 00 100. 00

Varying amounts of water from to 500 p.p.m. are wherein x is 1 or 2, R is a C to C hydrocarbyl group,

added to aliquots of the oil blend. A first set of aliquots R and R each are a hydrogen atom or C to C 2 hydrois stored at room temperature for 24 hours and observed. 75 carbyl group, and R is an amino-hydrocarbyl group of 9 the formula {-CH 9- ,NHR when x is 1, or tCHfl N+H R when x is 2, wherein n is 2 or 3 and R is a C to C hydrocarbyl group.

2. The composition of claim 1, wherein said metal is zinc, the alkyl group of said dithiophosphate has from 3 to 8 carbon atoms, as is 2, R is l 11 \CH2/s NNHzR and R is a substantially linear C to C aliphatic group. 3. The composition of claim 2, wherein R and R are each hydrogen and R is {-CH N+H C H 4. A lubricating oil composition comprising a major proportion of an oil of lubricating viscosity and about 10 References Cited UNITED STATES PATENTS PATRICK P. GARVIN, Primary Examiner A. H. METZ, Assistant Examiner 0.5 to 10 weight percent, based on the weight of said com- 15 position, of the additive composition of claim 1.

US. Cl. X.R. 

